Wax product

ABSTRACT

A method of making wax articles and lubricity to textile yarns in which paraffin wax having a particular melting temperature is heated to a temperature above the melting temperature and thereby melted. A mold is then filled with a molten wax while being chilled to a temperature. Thereafter, the mould and the wax in the mould are heated to a temperature substantially the same as the melting temperature and the wax is subsequently removed from the mould. The sequenced chilling and heating impart to the moulded wax a particular molecular structure which enhances lubricity.

This is a division of Ser. No. 729,363, filed Oct. 4, 1976, and nowabandoned, which in turn is a division of Ser. No. 625,601, filed Oct.24, 1975 and now U.S. Pat. No. 4,086,046.

BACKGROUND TO THE INVENTION

The invention relates to waxes such as paraffin wax, and to articlesmoulded therefrom, in particular, but not exclusively, wax rings for usein the lubrication of yarns in knitting machines.

DESCRIPTION OF THE PRIOR ART

It is know to mould articles from paraffin wax by pouring molten waxinto moulds and allowing it to solidify. Wax rings are at presentmanufactured in this way, wax being poured by hand into a plurality ofring-like moulds, which are emptied by hand after the wax has cooled.

SUMMARY OF THE INVENTION

The Applicant has discovered that wax rings can be made very quickly andefficiently by machine, but it has also been found, very surprisingly,that the wax rings produced by the machine have better lubricatingproperties than those produced previously. It is believed that theoperations to which the wax is subjected in the machine cause itsmolecular structure to be altered in a way which is beneficial to thelubricating properties. Tests carried out in the Textile Department ofthe University of Leeds using X-ray diffraction analysis have shownclearly that the structure of the wax differs from the known waxes andit appears that probably the most important factor in the change ofmolecular structure is the rate of cooling of the wax.

According to the invention the wax is solidified in a mould which isrefrigerated.

The wax may be melted by raising its temperature to its melting pointbut no higher.

The mould may be refrigerated using chilled fluid (e.g. water), forexample by passing the chilled fluid around the mould or throughpassages in the mould. The fluid may have a temperature in the range 0°to 15° centigrade, but it is preferred that the temperature is in therange 5° to 10° centigrade and a particularly suitable temperature hasbeen found to be 7° centigrade.

It is preferred that after the wax has been cooled it is again heated,for example to within 1° centrigrade of its melting point. The wax maybe heated by applying fluid (e.g. water) to the mould. The fluid may beat a temperature which is less than the melting temperature of the waxand it is preferred that the temperature of the fluid is 1° centigradebelow the melting temperature of the wax.

It is further preferred that after the wax has again been heated, it issubjected to pressure, for example by compressing it in the mould, or inanother mould.

The invention also provides paraffin wax which has been melted and thencooled in a refrigerated mould.

It has been estimated that the treatment to which the wax is subjectedby the method according to the invention varies the spacing betweenlayers of molecules, and accordingly, the invention further provides aparaffin wax comprising an assembly of molecules stacked together inlayers, having been increased by heat treatment. For a wax having amelting point in the range 62° C. to 66° C., the pitch may be increasedto above 36.5 Angstrom units. The thickness of each layer or the pitchof the stacking may lie in the range 38 to 39 Angstrom units, forexample it may be 38.7 Angstrom units.

The invention also provides a machine for moulding articles fromparaffin wax comprising a forming mould for receiving molten wax, andmeans to refrigerate the mould. Preferably there are a plurality offorming moulds. There may be fluid flow passages within each mould andmeans to pass refrigerated fluid (e.g. water) through the passages.

It is preferred that the machine includes means to pass heated fluid(e.g. water) through the fluid flow passages.

It is also preferred that the machine includes means to compress thewax. The machine may have a transfer mould to which articles solidifiedand softened in a forming mould may be transferred, there being means tocompress an article in the transfer mould. There may be a plurality oftransfer moulds.

The or each forming mould may comprise an open topped chamber with avertically movable base portion, and the or each transfer mould maycomprise an open bottomed chamber with a vertically movable top portion.

An article may be transferable from a forming mould to a transfer mouldby arranging the transfer mould above the forming mould and raising thebase portion of the forming mould to push the article upwardly into thetransfer mould.

An article may be compressed in a transfer mould by arranging thetransfer mould on a base member and moving the top portion of thetransfer mould downwardly to compress the article between the topportion and the base member.

Preferably a forming mould is movable between a refrigeration station, aheating station, and a transfer station. A mould may be mounted on aturntable for rotary movement from station to station.

A transfer mould may be movable between the transfer station and apressing station. A transfer mould may be arranged for linear movementbetween the transfer station and the pressing station along a line whichextends radially of the axis of rotation of the turntable.

A transfer mould may be movable beyond the pressing station to anejection station where the top portion of the or each transfer mould maybe moved downwardly to push an article out of the mould. The article maytend to stick to the face of the top portion in which case means may beprovided for removing the article from the face of the top portion.

The machine is preferably such that the temperature of the refrigeratedfluid and/or the temperature of the hot fluid and/or the pressure atwhich articles are compressed, can be varied.

A forming mould and the or each transfer mould preferably has acylindrical side wall and a cylindrical core so that articles may beproduced with a uniform annular cross-section. Preferably thecylindrical side wall and/or the cylindrical core have fluid flowpassages therethrough. It is further preferred that the cylindrical sidewall comprises, or is sheathed or otherwise surrounded by, heatinsulating material so that the temperature of the mould may be moreeasily controlled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of one embodiment of a machine according to theinvention;

FIG. 2 is a section on line II--II of FIG. 1;

FIG. 3 is a schematic representation of one forming mould of themachine; and

FIG. 4 is a cross-section through an alternative form of wax supplytank.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Referring first to FIGS. 1 to 3, the machine has a main frame 10, withan upstanding pedestal 11. The pedestal supports a vertical spindle 12on which a triangular turntable 13 is rotatably mounted.

Respectively mounted on the three faces of the triangular turntable arethree forming mould blocks 14, 15, 16.

Each mould block comprises eight parallel rows of eight moulds, so thatthere are sixty-four individual forming moulds in each block. One suchmould is represented schematically in FIG. 3. The mould defines anannular cylindrical mould space 50. The radially outer boundary of thisspace is defined by two concentric sleeves 51, 52 sealed together attheir ends except for an upper entry aperture 53 and a lower exitaperture 54. The radially inner boundary of the mould space is definedby a pair of concentric tubes 55, 56. The tube 55 is closed at its upperend but has an inlet conduit 57 at its lower end. The tube 56 is shorterthan the tube 55 and has an exit conduit 58 at its lower end. Thisconduit 58 passes through a hole in the wall of the tube 55 and issealed to the wall around the edges of this hole. Slidable within themould space is an annular cylindrical piston 59. The piston has radialdimensions which correspond to the radial dimensions of the mould spacebut the axial dimension of the piston is substantially smaller than thatof the mould space. Depending from the piston are two rods 60, 61,arranged at diametrically opposed positions. Secured to the lower end ofthe rods is an abutment plate 62.

Each forming mould, between the levels indicated in broken lines in FIG.3, is mounted in the mould block. The body of the block is of metal, forexample aluminium, but between the metal and the outer metal sleeve 51of each mould is a heat insulating sleeve of rubber (not shown).

The temperature of the mould may be controlled by passing hot or coldwater through the entry aperture 53 and inlet conduit 57, so that waterwill flow down the space between the sleeves 51, 52 and out of theaperture 54, and water will also flow up the tube 55, down the tube 56,and out of the exit conduit 58. The moulds are interconnected such thatwater may be supplied at a single inlet on the mould block, willcirculate through all sixty-four moulds, and emerge at another singleoutlet on the mould block.

In the position shown in FIG. 1 the mould 14 is at a refrigerationstation. A sub-frame 17 is pivoted at 18 to the main frame at therefrigeration station. The sub-frame is pivotable towards and away fromthe block 14 by the action of a double acting pneumatic ram 19 connectedbetween the mid-point of the sub-frame 17 and the pedestal 11. Thesub-frame carries two fluid connectors 20, 21. When the block 14 is inthe position shown and the sub-frame 17 is pivoted towards the block theconnectors 20, 21 respectively push open inlet and outlet valves on theblock and sealingly engage with the inlet and outlet of the block. Thefluid connectors are connected to a source of refrigerated water (notshown) so that the water can be pumped through the mould block,refrigerating each mould.

At the refrigeration station vertical guide columns 22 are secured tothe main frame above the mould block 14. Slidable on these columns is aframe 23 carrying a wax supply tank 24. The frame 23 and the tank can beraised and lowered by a pneumatic piston and cylinder combination 25connected to the frame 23 and mounted on overhead cantilever beams 26. Aplurality of passages lead downwardly from the tank 24, one passage foreach mould, and each passage leads to a point immediately above theassociated mould. Only one passage 27 is shown, for the sake ofsimplicity. The passage is defined by a telescopic arrangement of twotubes 28, 29, the upper tube being fixed to the tank 24 and the lowertube being rigidly fixed to the main frame. A valve arrangement 30ensures that when the tank 24 is in the raised position shown the upperand lower tubes are not in communication. When the tank is lowered usingthe piston and cylinder combination 25 however, the valve arrangementopens and molten wax flows from the tank 24 through the tubes 28 and 29and into each forming mould, through the open top of the mould.

In the position shown in FIG. 1 the mould block 15 is at a heatingstation. A ram-operated sub-frame (not shown but identical to sub-frame17) is mounted at the heating station and is operable to pass hot waterthrough the mould block 15.

Also in the position shown in FIG. 1 the mould block 16 is at a transferstation. From the transfer station a pair of parallel horizontal rails30 extend away from the pedestal 11 in a direction which is radial tothe spindle 12. The rails are supported on an extension 31 of the mainframe 10.

Slidable along the rails 30 is a transfer mould block 32. The mouldblock has eight rows of eight transfer moulds, one for each formingmould of the block 16. For simplicity only one transfer mould 33 isshown, and it comprises and open bottomed cylindrical sleeve 34 with asolid cylindrical core 35 and a vertically movable upper wall in theform of an annular piston 36. Connected to the piston is an upwardlyextending tubular piston rod 37 with an air inlet nozzle 38 at its upperend.

Mounted at the transfer station below the mould blocks is a liftplatform 39 powered by a pneumatic ram 40 connected to the main frame.Solidified wax rings are transferred to the transfer mould when thetransfer moulds are in registration with the forming moulds as shown, byraising the platform 39 to push the abutment plates 62 of the formingmoulds upwardly, hence raising the forming mould pistons 59 and drivingthe wax rings into the transfer mould. One wax ring 41 is shown in thetransfer mould.

Intermediate the ends of the rails 30 is a pressing station 42. Abolster 43 is secured to the frame extension 31 and carries a fixedlower press platen 44. Four guide columns 45 extend upwardly from thebolster and an upper press platen 48 is slidably mounted on the columns.Movement of the upper platen is controlled by a pneumatic ram 47 mountedat the top of the columns 45. The upper and lower platens are ofsufficient length to extend across the entire width of the transfermould block and are sufficiently wide to cover two rows of transfermoulds.

Beyond the pressing station there is an ejection station 48 where thereis means (not shown) to push the transfer mould pistons 36 downwardlyand to connect a source of compressed air to the inlet nozzles 38.

In operation the turntable 13 rotates clockwise (as viewed in FIG. 1)periodically in 120° steps and each forming mould block in turn receivesa charge of molten wax in each of its forming moulds while the mouldblock is chilled by circulation of refrigerated water. The wax rapidlysolidifies in the form of rings and at the next station the solidifiedwax is softened by the passage of hot water through the mould block. Atthe third station the softened wax rings are transferred to the transfermould blocks. Subsequently the transfer mould is moved along the rails30 by means not shown, until the first two rows of transfer moulds lieunder the upper press platen 44. The press platen is then lowered toengage sixteen of the nozzles 38 and hence depress sixteen of thepistons 36, compressing sixteen wax rings against the lower platen 44.The remainder of the wax rings are subsequently compressed, two rows ata time, and the transfer mould then moves to the ejection station 48where the pistons 36 are depressed further to push the wax rings out ofthe transfer moulds. Since the wax rings tend to stick to the lower faceof the pistons compressed air is blown through the hollow piston rods 37via the nozzles 38. The compressed air passes through passages (notshown) in the piston 36 to the lower face of each piston and blows thewax rings off the pistons. A receiving tray or removal conveyor (notshown) is arranged below the ejection station to catch the finished waxrings.

The use of a turntable and three forming mould blocks ensures that eachof the refrigeration, heating and transfer stations is in usesubstantially all the time. While one block is being refrigerated and isreceiving wax another block is being heated and the third block ishaving its wax rings removed, pressed and ejected.

One use for wax rings prepared using the machine and method of the aboveexample is in the lubrication of yarns for knitting. A conventionalmethod of preparing wax rings for use in the lubrication of yarns forknitting involves melting wax, pouring the wax into moulds, and allowingthe wax to cool under ambient temperature conditions. A sample of waxrings prepared using the method of the invention has been found to giveimproved results compared with known wax rings, in that yarns lubricatedusing wax rings according to the invention have exhibited lessfrictional resistance when passing through knitting yarn guides andneedles than yarns lubricated using known wax rings.

The said sample of wax rings was prepared from a paraffin wax having amelting point of 62°-66° C., indicating that the wax was ofheterogeneous composition, being made up of a range of differenthydrocarbons. The wax was heated to a temperature of 66° C. and thenpoured into moulds refrigerated by water at a temperature of 7° C. Afterthe wax had hardened the moulds were heated with water at 61° C. and thesoftened wax rings were removed and compressed in a hand operated press.

Samples of wax removed from the rings were subjected to X-raydiffraction analysis, as were samples removed from known rings. Theresultant X-ray reflections took the form of a series of concentricrings and from the intensity of the rings the following measurementswere obtained:

    ______________________________________                                                            Wax according to                                                     Known Wax                                                                              the invention                                             ______________________________________                                        Reflection A 36.3       38.7                                                  Reflection B 18.1       19.3                                                  Reflection C 12.15      12.8                                                  Reflection D 3.80       3.8                                                   Reflection E 3.41       3.41                                                  ______________________________________                                    

The measurements are in Angstrom units and relate to structuraldimensions of the molecules making up the wax. It is believed that thewax consists of an assembly of molecular layers stacked together, singlemolecules running from one face of a layer to the other face. It is alsobelieved that the figures for reflection A correspond to the repeatdistance (or pitch) between successive layers of the wax. The zig-zagchain molecules may be arranged either perpendicular to the faces of thelayers, in which case reflection A provides a measure of the actuallength of each molecule, or inclined at a constant angle to the faces ofthe layer. It is probable that reflections B and C are the second andthird order reflections of reflection A.

Since reflection A gives a significantly higher result for the waxaccording to the invention than for the known wax it is believed thatthe layer spacing that wax is greater than in conventional waxes. Thismay be because the bond angle between successive atoms in each molecularchain has increased, and/or because the angle of inclination of themolecules with respect to the layer faces has increased.

It is believed that reflections D and E, which are substantiallyidentical for the two waxes tested, relate to the spacing between waxmolecules in directions which are parallel to the faces of the waxlayers.

Turning now to FIG. 4, there is shown an alternative form of wax supplytank 24a, which in use is mounted in a fixed position at therefrigeration station. Mounted within the tank are sixty-four meteringtubes 70 extending upwardly from the base of the tank in eight rows ofeight. The tubes are positioned so that when a mould block is at therefrigeration station, the sixty-four tubes 70 are in registration withthe sixty-four forming moulds underneath. A valve-controlled outletnozzle 71 extends downwardly from each tube 70.

A wax feed pipe 72 extends into the tank and the wax is maintained at aconstant level which is just below the tops of the tubes 70, and isindicated by a dotted line 72.

To one side of the tubes 70 there is a wax displacement block 73 whichis mounted on the piston rod 74 of an air cylinder 75. The air cylinder75 is rigidly mounted on the top of the tank.

When it is desired to change the moulds of a mould block, the waxdisplacement block 73 is lowered into the wax, by operation of the aircylinder 75, raising the wax level to a new level which is above the topof the tubes 70. The tubes 70 thus fill and wax and when they are full,the block 73 is raised again, lowering the wax level below the tops ofthe full tubes 70. Each tube contains the same quantity of wax and thisis now transferred to the mould below by opening the associate valve 71.The process can then be repeated when the next mould block is positionedbelow the tank.

It will be seen that the quantity of wax which is metered into eachmould is dependent on the capacity of the tubes 70. In order to permitwax rings of different sizes to be produced, means are provided foraltering the capacity of the tubes 70, and hence altering the quantityof wax fed to the moulds. These means comprises sixty-four plungers 76,one for each tube 70, all the plungers being mounted on a common supportplatform 77. Movement of the platform 77 is controlled by a second aircylinder 78, the platform being connected to the piston rod 79 of thecylinder. The capacity of the tubes 76 varies according to how far theplungers project into the tubes 70 so by varying the height of theplatform 77, the size of the wax rings porduced can be varied.

The invention is not restricted to the details of the foregoingexamples. For instance, it is not essential to have three forming blockmoulds. There may be one, two, four or more blocks. Furthermore, it isnot essential that water be used to refrigerate and heat the mouldblocks. Other heat conveying fluids may be used.

The articles may be moulded from wax with the application of pressurebut without refrigeration.

It is not essential to use a wax having a melting point in the range 62°C. to 66° C. Waxes may for example be used having from 20 carbon atomsper molecule (melting point from 120° F. to 125° F.) to 40 carbon atomsper molecule (melting point from 150° F. to 155° F.) or from acombination of such waxes.

We claim:
 1. The molded wax article capable of imparting enhancedlubricity to textile yarns and consisting of a body of paraffin waxhaving a melting temperature in the range of from 62° C. to 66° C. and amolecular structure of layers spaced at a distance greater than 36.5angstrom units as measured by X-ray diffraction analysis.